In the paper “COMPRESSED AIR ENERGY STORAGE OFFERS FLEXIBILITY FOR LOW COST PROVIDERS OF ELECTRICITY”, presented at the “Power-Gen 1995”, Gavin W. Gaul of Westinghouse Electric Corporation, Michael McGill of Texas Power Corporation and Robert W. Kramer, Ph.D of Northern Indiana Public Service Company describe a gas storage power plant. The known gas storage power plant has a turbo group with two turbines, to be precise a high-pressure turbine and a low-pressure turbine, which are drive-connected to a generator. Furthermore, the gas storage power plant may comprise a plurality of compressor groups which can be operated independently of the turbo group and each comprise a compressor capable of being driven by an electric motor. The gas storage power plant possesses, moreover, a gas reservoir which is discharged via the turbo group in order to generate electrical energy and which can be charged with the aid of the compressor groups.
A gas storage power plant of this type is normally tied into what is known as a “Compressed Air Energy Storage System”, CAES system in shortened form. The basic idea of a CAES system is seen in transferring excess energy, generated by permanently operated conventional power plants during basic-load times, into the peak-load times by the cut-in of gas storage power plants, in order thereby, overall, to consume fewer resources for the production of electrical energy. This is achieved in that, with the aid of the cost-effective excess energy, air or another gas is pumped under relatively high pressure into a reservoir, out of which the air or the gas can be extracted, as required, in order to generate relatively costly current. This means that the energy is stored retrievably in the form of potential energy. For example, extensive coal or salt mines serve as reservoirs.
In this connection, a gas storage power plant is conventionally operated in such a way that the compressors for charging the gas reservoir are activated during a charging cycle and at the same time are driven by the associated electric motors. In this case, electrical energy is drawn off from the public power supply network. In this charging phase, the activation of the compressor groups takes place as a function of the available electrical energy. For feeding electrical energy into the public network, the turbines for discharging the gas reservoir are activated during a discharge cycle, and they drive the associated generator. The turbo group of the gas storage power plant is conventionally dimensioned as a function of the available gas reservoir, in such a way that as much electrical energy as possible can be fed into the public network over the entire current generation phase. The turbo group is therefore designed in terms of a maximization of the energy capable of being drawn off from the gas reservoir during the current generation phases.